<?php
/**
 * XmuSlh, web platform of Student Association Federation of Xiamen University
 * 
 * Rewritting one or some pages of StatusNet. 
 * To get the original version, please visit <http://status.net/>.
 * 
 * StatusNet, the distributed open-source microblogging tool
 * 
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * The Wrap class of the Safe_DataObject with caching system.
 * 
 * DB_DataObject开源数据库工具的一个包装类, 在许多系统调用中确保安全.
 * Memcached_DataObject是一个带服务器缓存的数据库对象.
 * 它将会根据情况对数据表进行Cache, 是访问数据库的次数减少.
 * 
 * TODO: Get more infomation from the open source project -- Memchache.
 * 
 * @author		ytukie <ytukie@gmail.com>
 * @version		0.1
 */

// XmuSlh only.
if ( !defined('XMUSLH')) { exit(1); }

class Memcached_DataObject extends Safe_DataObject
{
	/**
	 * Wrapper for DB_DataObject's static lookup using memcached
	 * as backing instead of an in-process cache array.
	 * 
	 * Reference.!
	 * 
	 * @param string	$class	classname of obect type to load.
	 * @param mixed 	$key	key field name, or value for primary key
	 * @param mixed		$value	key field value, or leave out for primary key lookup
	 * @return mixed	Memcached_DataObject subtype or false.
	 */
	function &staticGet($class, 
						$key, 
						$value = null)
	{
		// What's the meaning below?
		if (is_null($value)) {
			$value = $key;
			$cls = new $class;
			$keys = $cls->keys();
			$k = $keys[0];
			unset($cls);
		}
		
		$cls = Memcached_DataObject::getCached($class, $key, $value);
		if ($cls === false) {
			// Cache missing.
			$cls = DB_DataObject::factory($class);
			if (empty($cls)) {
				$cls = false;
				return $cls;
			}
			
			$result = $cls->get($key, $value);
			if ($result) {
				// Hit the cache!
				$cls->encache();
			} else {
				// Save the fact that no such row exists
				$cache = self::memcache($class, $key, $value);
				if ( !empty($cache)) {
					$ck = self::cachekey($class, $key, $value);
					$cache->set($ck, null);
				}
				
				$cls = false;
			}
		}
		
		return $cls;
	}
	
	/**
	 * FIXME: Should this return false on lookup fail to match staticGet?
	 */
	function pkeyGet($class, $kv)
	{
		$cls = Memcached_DataObject::multicache($class, $kv);
		if ($cls !== false) {
			return $cls;
		} else {
			$cls = DB_DataObject::factory($class);
			if (empty($cls) || PEAR::isError($cls)) {
				return false;
			}
			foreach ($kv as $k => $v) {
				$cls->$k = $v;
			}
			
			if ($cls->find(true)) {
				$cls->encache();
			} else {
				$cls = null;
				$cache = self::memcache();
				if (!empty($cache)) {
					$ck = self::multicacheKey($class, $kv);
					$cls->set($ck, null);
				}
			}
			
			return $cls;
		}
	}
	
	function insert()
	{
		$result = parent::insert();
		if ($result) {
			$this->fixupTimestamps();
			$this->encache();
		}
		
		return $result;
	}
	
	function update($orig = null)
	{
		if (is_object($orig) && $orig instanceof Memcached_DataObject) {
			// Might be different keys
			$orig->decache();
		}
		
		$result = parent::update($orig);
		if ($result) {
			$this->fixupTimestamps();
			$this->encache();
		}
		
		return $result;
	}
	
	function delete()
	{
		// While we still have the values.
		$this->decache();
		return parent::delete();
	}
	
	static function memcache()
	{
		// FIXME: Common!!!! 
		/*
		 * return common_memcache();
		 */
	}
	
	static function cacheKey($class, 
							 $key, 
							 $value)
	{
		if (is_object($class) || is_object($k) || (is_object($v) && !($v instanceof DB_DataObject_Cast))) {
			$e = new Exception();
			// FIXME: Common!!!!
			/*
			 * common_log(LOG_ERR, __METHOD__ . ' object in param: ' . 
			 * 		str_replace("\n", " ", $e->getTraceAsString()));
			 */
			$vstr = self::valueString($class, $key, $value);
			
			// FIXME: Common!!!!!
			/*
			 * return common_cache_key(strtolower($class) . ':' . $k . ':' . $vstr);
			 */
		}
	}
	
	static function getCached($class, 
							  $key, 
							  $value)
	{
		$cache = Memcached_DataObject::memcache();
		if ( !$cache) {
			return false;
		} else {
			$obj = $cache->get(Memcached_DataObject::cacheKey($class, $key, $value));
			if (0 == strcasecmp($class, 'User')) {
                // Special case for User
                if (is_object($obj) && is_object($obj->id)) {
                	/*
                	 *  common_log(LOG_ERR, "User " . $obj->nickname . " was cached with User as ID; deleting");
                	 */
                    $cache->delete(Memcached_DataObject::cacheKey($class, $key, $value));
                    return false;
                }
            }
            
            return $obj;
		}
	}
	
	function keyTypes()
	{
		// ini-based classes return number-indexed arrays. handbuilt
		// classes return column => keytype. Make this uniform.
		
		$keys = $this->keys();
		
		$keyskeys = array_keys($keys);
		
		if (is_string($keyskeys[0])) {
			return $keys;
		}
		
		global $_DB_DATAOBJECT;
		if ( !isset($_DB_DATAOBJECT['INI'][$this->_database][$this->__table . "__keys"])) {
			$this->databaseStructure();
		}
		
		return $_DB_DATAOBJECT['INI'][$this->_database][$this->__table . "__keys"];
	}
	
	/**
	 * FIXME: ?
	 * What an encache!
	 */
	function encache()
	{
		$cache = $this->memcache();
		
		if ( !$cache) {
			return false;
		} else if ($this->tableName() == 'user' && is_object($this->id)) {
			// Special case for User bug
			$e = new Exception();
			/*
			 * FIXME: Common!!!!!!
			 * common_log(LOG_ERR, __METHOD__ . 'caching user with User object as ID ' . 
			 * 				str_replace("\n", " ", $e->getTraceAsString()));
			 */
			return false;
		} else {
			$keys = $this->_allCacheKeys();
			
			foreach ($keys as $key) {
				$cache->set($key, $this);
			}
		}
	}
	
	/**
	 * FIXME: oh
	 * decache()
	 */
	function decache()
	{
		$class = $this->memcache();
		
		if ( !$cache) {
			return false;
		}
		
		$keys = $this->_allCacheKeys();
		
		foreach ($keys as $key) {
			$cache->delete($key, $this);
		}		
	}
	
	function _allcacheKeys()
	{
		$ckeys = array();
		
		$types = $this->keyTypes();
		ksort($types);
		
		$pkey = array();
		$pval = array();
		
		foreach ($types as $key => $type) {
			assert (!empty($key));
			
			if ($type == 'U') {
				if (empty($this->key)) {
					continue;
				}
				$ckeys[] = $this->cacheKey($this->tableName(), $key, self::valueString($this->$key));
			} else if ($type == 'K' || $type == 'N') {
				$pkey[] = $key;
				$pval[] = self::valueString($this->$key);
			} else {
				// Low level exception.
				throw new Exception("Unkonwn key type $key => $type for " . $this->tableName());
			}
		}
		
		assert(count($pkey) > 0);
		
		// XXX: should work for both compound and scalar pkeys
		$pvals = implode(',', $pval);
		$pkeys = implode(',', $pkey);
		
		$ckeys[] = $this->cacheKey($this->tableName(), $pkeys, $pvals);
		
		return $ckeys;
	}
	
	/**
	 * MultiCache()
	 */
	function multicache($class, $kv)
	{
		ksort($kv);
		$cache = self::memcache();
		
		if ( !$cache) {
			return false;
		} else {
			return $cache->get(self::multicache($class, $kv));
		}
	}
	
	static function multicacheKey($class, $kv)
	{
		ksort($kv);
		$pkeys = implode(',', array_keys($kv));
		$pvals = implode(',', array_values($kv));
		return self::cacheKey($class, $pkeys, $pvals);
	}
	
	/**
	 * TODO: getSearchengine($table);
	 * 
	function getSearchEngine($table)
    {
        require_once INSTALLDIR.'/lib/search_engines.php';
        static $search_engine;
        if (!isset($search_engine)) {
            if (Event::handle('GetSearchEngine', array($this, $table, &$search_engine))) {
                if ('mysql' === common_config('db', 'type')) {
                    $type = common_config('search', 'type');
                    if ($type == 'like') {
                        $search_engine = new MySQLLikeSearch($this, $table);
                    } else if ($type == 'fulltext') {
                        $search_engine = new MySQLSearch($this, $table);
                    } else {
                        // Low level exception. No need for i18n as discussed with Brion.
                        throw new ServerException('Unknown search type: ' . $type);
                    }
                } else {
                    $search_engine = new PGSearch($this, $table);
                }
            }
        }
        return $search_engine;
    }
	 * 
	 */
	function getSearchEngine($table) {}
	
	/**
	 * FIXME: Common!!!!!
	 * cachedQuery()
	 */
	static function cachedQuery($class, 
								$query, 
								$expiry = 3600)
	{
		$cache = Memcached_DataObject::memcache();
		if ( !$cache) {
			$inst = new $class();
			$inst->query($query);
			return $inst;
		}
		
		$key_part = common_keysize($class) . ':' . md5($query);
		$ckey = common_cache_key($key_part);
		$stored = $cache->get($ckey);
		
		// FIXME: ArrayWrapper!!!
		if ($stored !== false) {
			return new ArrayWrapper($stored);
		}
		
		$inst = new $class();
		$inst->query($query);
		$cached = array();
		while ($inst->fetch()) {
			$cached[] = clone($inst);
		}
		$inst->free();
		// FIXME: Cache!!!!
		$cache->set($ckey, $cached, Cache::COMPRESSED, $expiry);
		return new ArrayWrapper($cached);
	}
	
	/**
	 * FIXME: Commone!!!!
	 * 
	 * Sends query to database - this is the private one that must work
	 * - internal functions use this rather than $this->query().
	 */
	function _query($string)
	{
		/*
	 	if (common_config('db', 'annotate_queries')) {
            $string = $this->annotateQuery($string);
        }
        */
		
		$start = microtime(true);
		$result = null;
		
		// common_perf_counter('query', $string);
        $result = parent::_query($string);
        
        $delta = microtime(true) - $start;
        
        /*
	 	$limit = common_config('db', 'log_slow_queries');
        if (($limit > 0 && $delta >= $limit) || common_config('db', 'log_queries')) {
            $clean = $this->sanitizeQuery($string);
            common_log(LOG_DEBUG, sprintf("DB query (%0.3fs): %s", $delta, $clean));
        }
        */
        
        return $result;
	}

	/**
	 * Find the first caller in the stack trace that's not a
	 * low-level database function and add a comment to the 
	 * query string. This should then be visible in process lists
	 * and slow query logs, to help identify problem areas.
	 * 
	 * Also marks whether this was a web GET/POST or which daemon
	 * was running it.
	 */
	function annotateQuery($string)
	{
		$ignore = array('annotateQuery', 
						'_query', 
						'query', 
						'get', 
						'insert',
						'delete',
						'update',
						'find');
		$ignoreStatic = array('staticGet',
							  'pkeyGet',
							  'cacheQuery');
		$here = get_class($this);
		$bt = debug_backtrace();
		
	// Find the first caller that's not us?
        foreach ($bt as $frame) {
            $func = $frame['function'];
            if (isset($frame['type']) && $frame['type'] == '::') {
                if (in_array($func, $ignoreStatic)) {
                    continue;
                }
                $here = $frame['class'] . '::' . $func;
                break;
            } else if (isset($frame['type']) && $frame['type'] == '->') {
                if ($frame['object'] === $this && in_array($func, $ignore)) {
                    continue;
                }
                if (in_array($func, $ignoreStatic)) {
                    continue; // @fixme this shouldn't be needed?
                }
                $here = get_class($frame['object']) . '->' . $func;
                break;
            }
            $here = $func;
            break;
        }

        if (php_sapi_name() == 'cli') {
            $context = basename($_SERVER['PHP_SELF']);
        } else {
            $context = $_SERVER['REQUEST_METHOD'];
        }

        // Slip the comment in after the first command,
        // or DB_DataObject gets confused about handling inserts and such.
        $parts = explode(' ', $string, 2);
        $parts[0] .= " /* $context $here */";
        return implode(' ', $parts);
    }
    
    /**
     * Sanitize a query for loggin
     */
    function sanitizeQuery($srting)
    {
    	$string = preg_replace('/\s+/', ' ', $string);
    	$string = trim($string);
    	return $string;
    }
    
    /**
     * We overload so that 'SET NAMES "utf8"' is called for 
     * each connection
     */
function _connect()
    {
        global $_DB_DATAOBJECT;

        $sum = $this->_getDbDsnMD5();

        if (!empty($_DB_DATAOBJECT['CONNECTIONS'][$sum]) &&
            !PEAR::isError($_DB_DATAOBJECT['CONNECTIONS'][$sum])) {
            $exists = true;
        } else {
            $exists = false;
       }

        // @fixme horrible evil hack!
        //
        // In multisite configuration we don't want to keep around a separate
        // connection for every database; we could end up with thousands of
        // connections open per thread. In an ideal world we might keep
        // a connection per server and select different databases, but that'd
        // be reliant on having the same db username/pass as well.
        //
        // MySQL connections are cheap enough we're going to try just
        // closing out the old connection and reopening when we encounter
        // a new DSN.
        //
        // WARNING WARNING if we end up actually using multiple DBs at a time
        // we'll need some fancier logic here.
        if (!$exists && !empty($_DB_DATAOBJECT['CONNECTIONS']) && php_sapi_name() == 'cli') {
            foreach ($_DB_DATAOBJECT['CONNECTIONS'] as $index => $conn) {
                if (!empty($conn)) {
                    $conn->disconnect();
                }
                unset($_DB_DATAOBJECT['CONNECTIONS'][$index]);
            }
        }

        $result = parent::_connect();

        if ($result && !$exists) {
            $DB = &$_DB_DATAOBJECT['CONNECTIONS'][$this->_database_dsn_md5];
            if (common_config('db', 'type') == 'mysql' &&
                common_config('db', 'utf8')) {
                $conn = $DB->connection;
                if (!empty($conn)) {
                    if ($DB instanceof DB_mysqli) {
                        mysqli_set_charset($conn, 'utf8');
                    } else if ($DB instanceof DB_mysql) {
                        mysql_set_charset('utf8', $conn);
                    }
                }
            }
            // Needed to make timestamp values usefully comparable.
            if (common_config('db', 'type') == 'mysql') {
                parent::_query("set time_zone='+0:00'");
            }
        }

        return $result;
    }
    
    // XXX: largely cadged from DB_DataObject

    function _getDbDsnMD5()
    {
        if ($this->_database_dsn_md5) {
            return $this->_database_dsn_md5;
        }

        $dsn = $this->_getDbDsn();

        if (is_string($dsn)) {
            $sum = md5($dsn);
        } else {
            /// support array based dsn's
            $sum = md5(serialize($dsn));
        }

        return $sum;
    }

    function _getDbDsn()
    {
        global $_DB_DATAOBJECT;

        if (empty($_DB_DATAOBJECT['CONFIG'])) {
            DB_DataObject::_loadConfig();
        }

        $options = &$_DB_DATAOBJECT['CONFIG'];

        // if the databse dsn dis defined in the object..

        $dsn = isset($this->_database_dsn) ? $this->_database_dsn : null;

        if (!$dsn) {

            if (!$this->_database) {
                $this->_database = isset($options["table_{$this->__table}"]) ? $options["table_{$this->__table}"] : null;
            }

            if ($this->_database && !empty($options["database_{$this->_database}"]))  {
                $dsn = $options["database_{$this->_database}"];
            } else if (!empty($options['database'])) {
                $dsn = $options['database'];
            }
        }

        if (!$dsn) {
            // TRANS: Exception thrown when database name or Data Source Name could not be found.
            throw new Exception(_("No database name or DSN found anywhere."));
        }

        return $dsn;
    }

    static function blow()
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

        $args = func_get_args();

        $format = array_shift($args);

        $keyPart = vsprintf($format, $args);

        $cacheKey = common_cache_key($keyPart);

        return $c->delete($cacheKey);
    }

    function fixupTimestamps()
    {
        // Fake up timestamp columns
        $columns = $this->table();
        foreach ($columns as $name => $type) {
            if ($type & DB_DATAOBJECT_MYSQLTIMESTAMP) {
                $this->$name = common_sql_now();
            }
        }
    }

    function debugDump()
    {
        common_debug("debugDump: " . common_log_objstring($this));
    }

    function raiseError($message, $type = null, $behaviour = null)
    {
        $id = get_class($this);
        if (!empty($this->id)) {
            $id .= ':' . $this->id;
        }
        if ($message instanceof PEAR_Error) {
            $message = $message->getMessage();
        }
        // Low level exception. No need for i18n as discussed with Brion.
        throw new ServerException("[$id] DB_DataObject error [$type]: $message");
    }

    static function cacheGet($keyPart)
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

        $cacheKey = common_cache_key($keyPart);

        return $c->get($cacheKey);
    }

    static function cacheSet($keyPart, $value, $flag=null, $expiry=null)
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

        $cacheKey = common_cache_key($keyPart);

        return $c->set($cacheKey, $value, $flag, $expiry);
    }

    static function valueString($v)
    {
        $vstr = null;
        if (is_object($v) && $v instanceof DB_DataObject_Cast) {
            switch ($v->type) {
            case 'date':
                $vstr = $v->year . '-' . $v->month . '-' . $v->day;
                break;
            case 'blob':
            case 'string':
            case 'sql':
            case 'datetime':
            case 'time':
                // Low level exception. No need for i18n as discussed with Brion.
                throw new ServerException("Unhandled DB_DataObject_Cast type passed as cacheKey value: '$v->type'");
                break;
            default:
                // Low level exception. No need for i18n as discussed with Brion.
                throw new ServerException("Unknown DB_DataObject_Cast type passed as cacheKey value: '$v->type'");
                break;
            }
        } else {
            $vstr = strval($v);
        }
        return $vstr;
    }
}